Enguerrand entered the service of Hugues de Bouville, chamberlain and secretary of Philip IV, as a squire, and then was attached to the household of Queen Jeanne, who made him one of the executors of her will. He married her god-daughter, Jeanne de St Martin. In 1298 he received the custody of the castle of Issoudun.

Possessed of an ingratiating manner, politic, learned and astute, he acted as an able instrument in carrying out Philip's plans, and received corresponding confidence. He shared the popular odium which Philip incurred by debasing the coinage. He acted as the agent of Philip in his contest with Louis, Count of Nevers, the son of Robert III of Flanders, imprisoning Louis and forcing Robert to surrender Lille, Douai and Béthune.

This soon came to a head when the princes of the blood, eager to fight the Flemings, were disappointed by his negotiating a peace in September. He was accused of receiving bribes, and Charles of Valois denounced him to the king himself; but Philip stood by him and the attack was of no avail. The death of Philip IV on November 29, 1314 was a signal for a reaction against his policy. The feudal party, whose power the king had tried to limit, turned on his ministers and chiefly on his chamberlain.

Enguerrand was arrested by Louis X at the instigation of Charles of Valois, and twenty-eight articles of accusation including charges of receiving bribes were brought against him. He was refused a hearing; but his accounts were correct, and Louis was inclined to spare him anything more than banishment to the island of Cyprus. Charles then brought forward a charge of sorcery which was more effectual. He was condemned at once and hanged on the public Gibbet of Montfaucon, protesting that in all his acts he had only been carrying out Philip's commands (April 30, 1315).

Louis X seems to have repented of his treatment of Marigny, and left legacies to his children. When his chief enemy, Charles of Valois, lay dying in 1325, he was stricken with remorse and ordered alms to be distributed among the poor of Paris with a request to pray for the souls of Enguerrand and Charles.

Marigny founded the collegiate church of Nôtre Dame d'Ecouis near Rouen in 1313. He was twice married, first to Jeanne de St Martin, by whom he had three children, Louis, Marie and Isabelle (who married Robert, son of Robert de Tancarville); and the second time to Alips de Mons.

In popular culture, he was a major character in Les Rois Maudits (The Accursed Kings), a series of historical novels by Maurice Druon, which were adapted into mini-series in the 1970s, and again in 2005.